US 2004/0201073 A1 · Red/green pixel with simultaneous exposure and improved MTF

Abstract

A pixel for detecting red and greed light is a single pixel is described. The pixel comprises a deep N well formed in a P type epitaxial substrate. The pixel comprises a deep N well formed in a P type epitaxial substrate. A number of P wells, which are used as the sensor nodes, are formed in the deep N well. The use of these P wells as the sensor nodes improves the modulation transfer function. The depth of the deep N well is about equal to the depth of hole electron pairs generated by red light in silicon. The depth of the P wells is about equal to the depth of hole electron pairs generated by green light in silicon. A red/green signal is determined at each P well by determining the potentials between each of the P wells and the deep N well after a charge integration cycle with the P wells and the deep N well isolated. A green signal is determined at each P well by determining the potentials between each of the P wells and the deep N well after a charge integration cycle with the P wells isolated and the deep N well held at a fixed positive voltage. A red signal at each P well is determined by subtracting the green signal at that P well from the red/green signal at that P well. The invention can take advantage of the fact that the human perception of a green signal is green, the human perception of a red signal is red, and the human perception of a red/green signal is red. The invention also works if P regions are substituted for N regions and N regions substituted for P regions.

Claims30

Dependent claims

A method of extracting red and green signals from an active pixel sensor, comprising:

providing a pixel comprising a P type silicon substrate, a deep N well formed in said substrate, a number of P wells formed in said deep N well, an N+ region formed in each of said P wells, and a P+ region formed in said deep N well, wherein said deep N well has a first depth which is about equal to the depth of hole electron pairs generated in silicon by red light and each of said P wells has a second depth which is about equal to the depth of hole electron pairs generated in silicon by green light;
electrically isolating said P wells and said deep N well, after resetting the potential between each of said P wells and said substrate to a first voltage and the potential between said deep N well and said substrate to a second voltage, accumulating charge at the PN junctions between each of said P wells and said deep N well, and determining the potential between each of said P wells and said deep N well, wherein the potential between each of said P wells and said deep N well provides a red/green signal at each of said P wells;
electrically isolating said P wells and maintaining said deep N well at a third voltage, after resetting the potential between each of said P wells and said substrate to said first voltage and the potential between said deep N well and said substrate to said second voltage, accumulating charge at the PN junctions between each of said P wells and said deep N well, and determining the potential between each of said P wells and said deep N well, wherein the potential between each of said P wells and said deep N well provides a green signal at each of said P wells;
and
determining a red signal at each of said P wells by subtracting said green signal at each of said P wells from said red/green signal at that said P well.

2 more elements

A method of extracting red and green signals from an active pixel sensor, comprising:

providing a pixel comprising an N type silicon substrate, a deep P well formed in said substrate, a number of N wells formed in said deep P well, a P+ region formed in each of said N wells, and an N+ region formed in said deep P well, wherein said deep P well has a first depth which is about equal to the depth of hole electron pairs generated in silicon by red light and each of said N wells has a second depth which is about equal to the depth of hole electron pairs generated in silicon by green light;
electrically isolating said N wells and said deep P well, after resetting the potential between each of said N wells and said substrate to a first voltage and the potential between said deep P well and said substrate to a second voltage, accumulating charge at the PN junctions between each of said N wells and said deep P well, and determining the potential between each of said N wells and said deep P well, wherein the potential between each of said N wells and said deep P well provides a red/green signal at each of said N wells;
electrically isolating said N wells and maintaining said deep P well at a third voltage, after resetting the potential between each of said N wells and said substrate to said first voltage and the potential between said deep P well and said substrate to said second voltage, accumulating charge at the PN junctions between each of said N wells and said deep P well, and determining the potential between each of said N wells and said deep P well, wherein the potential between each of said N wells and said deep P well provides a green signal at each of said N wells;
and
determining a red signal at each of said N wells by subtracting said green signal at each of said N wells from said red/green signal at that said N well.

2 more elements

A method of extracting red and green signals from an active pixel sensor, comprising:

providing a pixel comprising a P type silicon substrate, a deep N well formed in said substrate, a number of P wells formed in said deep N well, an N+ region formed in each of said P wells, and a P+ region formed in said deep N well, wherein said deep N well has a first depth which is about equal to the depth of hole electron pairs generated in silicon by red light and each of said P wells has a second depth which is about equal to the depth of hole electron pairs generated in silicon by green light;
resetting the potential between each of said P wells and said substrate to a first voltage and the potential between said deep N well and said substrate to a second voltage during a first reset period;
electrically isolating said P wells and said deep N well, and accumulating charge at the PN junctions between each of said P wells and said deep N well during a first charge integration period, wherein said first charge integration period immediately follows said first reset period;
determining the potential between each of said P wells and said deep N well at the end of said first charge integration period;
resetting the potential between each of said P wells and said substrate to said first voltage and the potential between said deep N well and said substrate to said second voltage during a second reset period;
electrically isolating said P wells, maintaining the potential between said deep N well and said substrate at a third voltage, and accumulating charge at the PN junctions between each of said P wells and said deep N well during a second charge integration period, wherein said second charge integration period immediately follows said second reset period;
determining the potential between that each of said P wells and said deep N well at the end of said second charge integration period;
determining a red/green signal at each of said P wells, wherein said red/green signal at each of said P wells is the potential between that said P well and said deep N well at the end of said first charge integration period;
determining a green signal at each of said P wells, wherein said green signal at each of said P wells is the potential between that said P well and said deep N well at the end of said second charge integration period;
and
determining a red signal at each of said P wells by subtracting said green signal at each of said P wells from said red/green signal at that said P well.

8 more elements

A method of extracting red and green signals from an active pixel sensor, comprising:

providing a pixel comprising an N type silicon substrate, a deep P well formed in said substrate, a number of N wells formed in said deep P well, a P+ region formed in each of said N wells, and an N+ region formed in said deep P well, wherein said deep P well has a first depth which is about equal to the depth of hole electron pairs generated in silicon by red light and each of said N wells has a second depth which is about equal to the depth of hole electron pairs generated in silicon by green light;
resetting the potential between each of said N wells and said substrate to a first voltage and the potential between said deep P well and said substrate to a second voltage during a first reset period;
electrically isolating said N wells and said deep P well, and accumulating charge at the PN junctions between each of said N wells and said deep P well during a first charge integration period, wherein said first charge integration period immediately follows said first reset period;
determining the potential between that each of said N wells and said deep P well at the end of said first charge integration period;
resetting the potential between each of said N wells and said substrate to said first voltage and the potential between said deep P well and said substrate to said second voltage during a second reset period;
electrically isolating said N wells, maintaining the potential between said deep P well and said substrate at a third voltage, and accumulating charge at the PN junctions between each of said N wells and said deep P well during a second charge integration period, wherein said second charge integration period immediately follows said second reset period;
determining the potential between each of said N wells and said deep P well at the end of said second charge integration period;
determining a red/green signal at each of said N wells, wherein said red/green signal at each of said N wells is the potential between that said N well and said deep P well at the end of said first charge integration period;
determining a green signal at each of said N wells, wherein said green signal at each of said N wells is the potential between that said N well and said deep P well at the end of said second charge integration period;
and
determining a red signal at each of said N wells by subtracting said green signal at each of said N wells from said red/green signal at that said N well.

8 more elements

Dependencies are inferred from the claim text.

Red/green pixel with simultaneous exposure and improved MTF

Life of this patent

Red/green pixel with simultaneous exposure and improved MTF

Life of this patent

Abstract

Claims30